A quick presentation.
In the past, I worked as an engineer for ITT, in a Belgian subsidiary named Bell Telephone Mfg Cy.
Bell Telephone (BTMC) was in charge of the comercial deployement in Belgium and the Netherlands via her Business Systems Division.
A friend and collegue working in the Business Division was able to get a naked board from the production plant (Basildon, Essex). We have decided to remove the white print and green overlay in order to return the board to the shiny tin plated paths. Then we have requested the company photo department to make a « plan » film of both sides, scale 1/1. I have etched 5 printed board for my friend and one for me in order to build computers. It was just a crazy job to etch at home such a giant board with so thin tracks, but it worked.
It was also a crazy job to build the computer: we had to use special sockets to be soldered on both sides.
I still have that board hanging on the wall in my attic.
I have used that computer during 2 or 3 years, then I have removed the components to move them on an Apple II clone board with plated through holes, bought in Malaysia while I was working over there.I have just found a few day's ago the Engineering wall art drawing in my old stuff. (see my other post with that schematic)
I have scanned and enhanced all my interesting documents realted to the ITT-2020 as we have exchanged these documents during the real ITT-2020 computer prototyping.
My own ITT-2020 and the two ITT disk drives are prototypes developed back in 1979-1980.
Now the most interesting thing is that I have found the schematics, Service manual from Bell Telephoen Mfg Cy and a few documents coming from the Apple Lab at the time.
Sorry for the multiple files, Proton Drive refuses to syn a larger .zip file.
DOWNLOAD LINKS
ITT_2020_SYSTEM_PARTS_LIST.pdf
ITT-2020_SECAM VIDEO ENCODER.pdf
ITT_2020_VIDEO_TIP_ITT_GERMANY.pdf
ITT_2020_PROCESSOR_AND_CLOCK.pdf
DIAGNOSTIC_LOGIC_BOARD_SHEET-2.pdf
DIAGNOSTIC_LOGIC_BOARD_SHEET-1.pdf
DIAGNOSTIC_LOGIC_BOARD_SHEET-3.pdf
PALSOFT_CHANGES-VS-APPLE_FOR_ITT-2020-1978.pdf
HIRES_WITH_PAL-SECAM_ITT-2020.pdf
APPLE-LAB_DISK-II_TROUBLESHOOTING_LEVEL_II.pdf
APPLE_LAB_DISK-II_TECHNICAL_LEVEL-II.pdf
ITT-2020_SERVICE_MANUAL_BTMC.pdf
Enjoy.
Yves
And here you have the download link to the giant ITT-2020 schematic (105 cm X 72 cm) in colors made by ITT.
It can be considered as Engineering Wall Art.
Giant ITT-2020 link
Sory there are stitching glitches.
Yves
Thanks for the schematics. I haven't looked at them yet, but I'll do so when I have a moment. The ITT-2020 was an interesting design. I wonder if this computer had problems reading floppy disks at such different CPU clock speeds?
Hello, I had always reliability problems with my "silver" ITT drives.
I guess it was due to the prototype hand soldered analog circuit.
The Disk Drive interface in slot #6 is common with the Apple II.
When I use original Apple Disk II or a Shinon slim drive, I have no issue.
Yves
Thank you for the documents. Too bad this computer was so incompatible with the apple2 which created a software vacuum for it. Do you happen to have any docs/schematics for the TT_2020_Hires_Conversion_Board? https://en.wikipedia.org/wiki/ITT_2020#/media/File:ITT_2020_Hires_Conversion_Board.jpg
Hello,
There is a conversion board in my IT-2020.
I have built it myself in the 80's and I have found the transparent to make the PCB.
Unfortunately, I have not (yet) found the schematic.
If I find it, I will publish it here.
Yves
The HIRES conversion card that is in my ITT-2020 is of that type, but with a switch for ITT-2020 or Apple mode.
https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/ITT_2020_Hires_Conversion_Board.jpg/250px-ITT_2020_Hires_Conversion_Board.jpg
The 74LS166 on the mainboard had to be removed to plug in the ribbon cable connected to the daughter board.
I do not remember where I have found the information to make a PCB board for that Hires converter.
Yves